Biogeochemical Observations from Profiling Floats - The Oxygen Success Story and More to Come

Prof. Dr. Arne Körtzinger
IFM-GEOMAR, Leibniz-Institute for Marine Sciences Kiel
Duesternbrooker Weg 20
D-24105 Kiel
Germany

Modern oceanography has to provide answers on how global change will impact on the physical and chemical environment of the ocean and how this might cascade through marine ecosystems and potentially feed back into the climate system. This exciting and daunting task that major scientific programmes such as CLIVAR, SOLAS, and IMBER have adopted, requires innovative observational approaches that have to be used in a comprehensive and highly coordinated fashion. Special emphasis lies on the surface ocean, i.e the upper 100 m of the water column, where our long-term autonomous observational capabilities are still most severely limited. The ARGO profiling float observatory is a major success story in observational oceanography that marine biogeochemists have always been envious of. Due to the lack of suitable chemical and biological sensors they so far largely missed this great opportunity. However, new sensor and miniaturized instruments are being developed and major technological breakthroughs have been made or are to be expected soon. The recent advent of a new optode-based oceanographic oxygen sensor is such a quantum leap which allows precise and long-term stable measurements from profiling floats. Examples will be shown from the Labrador Sea, the tropical Atlantic Ocean as well as the Weddell Sea which illustrate the high quality and scientific potential of such measurements. Furthermore, the profiling float technology provides observational capabilities that extend beyond ARGO-style mission and include bi-directionality, recovery options and “virtual mooring” applications etc. Plans and ideas in this context will be shared.


References
Joos, F., G.-K. Plattner, T.F. Stocker, A. Körtzinger, and D.W.R. Wallace (2003). Trends in marine dissolved oxygen: Implications for ocean circulation changes and the carbon budget. EOS Trans. AGU 84: 197-204.
Körtzinger, A., J. Schimanski, U. Send, and D.W.R. Wallace (2004). The ocean takes a deep breath. Science 306, 1337.
Körtzinger, A., J. Schimanski, and U. Send (2005). High-quality oxygen measurements from profiling floats: A promising new technique, J. Atm. Ocean. Techn. 22, 302-308.
Tengberg, A., J. Hovdenes, J.H. Andersson, O. Brocandel, R. Diaz, D. Hebert, T. Arnerich, C. Huber, A. Körtzinger, A. Khripounoff, F. Rey, C. Rönning, J. Schimanski, S. Sommer and A. Stangelmayer (2005). Evaluation of a life time based optode to measure oxygen in aquatic systems. Limnol. Oceanogr.: Methods, submitted.